Sensor misalignment compensation

ABSTRACT

Camera compensation methods and systems that compensate for misalignment of sensors/camera in stereoscopic camera systems. The compensation includes identifying a pitch angle offset between a first camera and a second camera, determining misalignment of the first and second cameras from the identified pitch angle offset, determining a relative compensation delay responsive to the determined misalignment, introducing the relative compensation delay to image streams produced by the cameras, and producing a stereoscopic image on a display from the first and second image streams with the introduced delay.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.17/180,249 filed on Feb. 19, 2021, which is a continuation of U.S.patent application No. 16/706,162 filed on Dec. 6, 2019, both of whichare incorporated herein by reference in their entirety.

TECHNICAL FIELD

The present subject matter relates to wearable devices, e.g., eyeweardevices, having stereoscopic camera systems and techniques forcompensating for differences in pitch between sensors/cameras of thestereoscopic camera systems.

BACKGROUND

Stereoscopic camera systems utilize a pair of sensors/cameras to captureimages of a scene from two viewpoints. A conventional camera in suchsystems typically utilizes either a charge coupled device (CCD) sensoror a complementary metal oxide semiconductor (CMOS) sensor to capture animage frame of a scene. CCD sensors typically use a global shutter,which simultaneously captures the entire frame. CMOS sensors, on theother hand, typically use a rolling shutter, which sequentially exposesdifferent parts of the frame at different points in time.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawing figures depict one or more implementations, by way ofexample only, not by way of limitations. In the figures, like referencenumerals refer to the same or similar elements with a letter designationadded to differentiate between the same or similar elements. The letterdesignation may be dropped when the same or similar elements arereferred to collectively or when referring to a non-specific one of thesame or similar elements.

FIG. 1A is a side view of an example hardware configuration of aneyewear device utilized in a camera misalignment compensation system.

FIG. 1B is a top cross-sectional view of a right electronic housing ofthe eyewear device of FIG. 1A depicting a right visible light camera ofa depth-capturing camera, and a circuit board.

FIG. 1C is a left side view of an example hardware configuration of aneyewear device of FIG. 1A, which shows a left visible light camera ofthe depth-capturing camera.

FIG. 1D is a top cross-sectional view of a left electronic housing ofthe eyewear device of FIG. 1C depicting the left visible light camera ofthe depth-capturing camera, and the circuit board.

FIG. 2A is a side view of another example hardware configuration of aneyewear device utilized in the camera misalignment compensation system,which shows the right visible light camera and a depth sensor of thedepth-capturing camera to generate an initial depth image of a sequenceof initial depth images (e.g., in an initial video).

FIGS. 2B and 2C are rear views of example hardware configurations of theeyewear device, including two different types of image displays.

FIG. 3 shows a rear perspective sectional view of the eyewear device ofFIG. 2A depicting an infrared camera of the depth sensor, a frame front,a frame back, and a circuit board.

FIG. 4 is a cross-sectional view taken through the infrared camera andthe frame of the eyewear device of FIG. 3.

FIG. 5 shows a rear perspective view of the eyewear device of FIG. 2Adepicting an infrared emitter of the depth sensor, the infrared cameraof the depth sensor, the frame front, the frame back, and the circuitboard.

FIG. 6 is a cross-sectional view taken through the infrared emitter andthe frame of the eyewear device of FIG. 5.

FIG. 7 depicts an example of a pattern of infrared light emitted by theinfrared emitter of the depth sensor and reflection variations of theemitted pattern of infrared light captured by the infrared camera of thedepth sensor of the eyewear device to measure depth of pixels in a rawimage to generate the initial depth images from the initial video.

FIG. 8A depicts an example of infrared light captured by an infraredcamera of a depth sensor as an infrared image and visible light capturedby a visible light camera as a raw image to generate an initial depthimage of a scene.

FIG. 8B depicts an example of visible light captured by the left visiblelight camera as left raw image and visible light captured by the rightvisible light camera as a right raw image to generate the initial depthimage of a three-dimensional scene.

FIG. 8C depicts initial images captured using visible light cameras.

FIG. 8D depicts the images of FIG. 8C after rectification andcompensation to obtain calibrated images.

FIG. 8E depicts a graph showing readout times for image rows for acamera having a rolling shutter in accordance with the prior art.

FIG. 8F depicts images captured by a stereoscopic camera system in astatic system where the cameras of the camera system have differentpitch angles.

FIG. 8G depicts images captured by a stereo camera system in a dynamicsystem where the cameras of the camera system have different pitchangles and the camera is moving vertically.

FIG. 9 is a high-level functional block diagram of an example cameramisalignment compensation system including the eyewear device with adepth-capturing camera to generate initial depth images, a mobiledevice, and a server system connected via various networks.

FIG. 10 shows an example of a hardware configuration for the mobiledevice of the camera misalignment compensation system of FIG. 9.

FIGS. 11A, 11B, and 11C are flowcharts of methods the cameramisalignment compensation system implements to compensate formisalignment of cameras in a stereoscopic camera system.

DETAILED DESCRIPTION

In typical stereoscopic camera systems, the sensors/cameras aresynchronized and operate in a master-slave model. The cameras are drivenby the same clock and use the same exposure settings. The cameras of adevice may be misaligned (e.g., on the Y-axis; vertical axis) due tomechanical misalignment tolerances during assembly at the factory.Misalignment of the cameras cause feature points from a scene to beprojected to different sensor lines. While stereo calibration can oftencompensate for these differences in static scenes, they may not be ableto do so for moving objects and/or when the observer is moving.

Assuming a feature is projected to line Y1 on a first sensor (sensorl)and to line Y2 on a second sensor (sensor2), lines Y1 and Y2 are exposedat different times when using a rolling shutter read out method (whichis typical for CMOS sensors). Assuming it takes time, t, to read out asingle sensor line, the time difference, T, equals t*abs(Y1−Y2). If theobject or the cameras are moving, this time difference will result indifferent positions of the feature point on two sensors/cameras, whichcomplicates stereo matching of the feature point. The impact of thismisalignment may be addressed after exposure/capture of the images orbefore exposure/capture of the images. In one approach the verticalblanking interval (V-blank period) is maximized to reduce time ‘t’ andminimize ‘T’. In another approach, exposure delay counted in sensorlines (i.e., in ‘t’ units) is introduced in order to postpone readoutfrom one of the sensors such that lines Y1 and Y2 are exposed atsubstantially the same time. Exposure delay is a feature available inmodern sensors from, for example, Sony Corporation of Minato, Japan.During stereo calibration at the factory, the misalignment informationmay be stored on the device. On bootup, the calibration data is read outand the misalignment angle is converted into the required delay inlines. Prior to camera activation the sensors are configured with thedelay times. The autoexposure algorithm may be adjusted to account forthe worst-case delay.

In this detailed description, numerous specific details are set forth byway of examples in order to provide a thorough understanding of therelevant teachings. However, it should be apparent to those skilled inthe art that the present teachings may be practiced without suchdetails. In other instances, description of well-known methods,procedures, components, and circuitry are set forth at a relativelyhigh-level, without detail, in order to avoid unnecessarily obscuringaspects of the present teachings.

As used herein, the term “coupled” or “connected” refers to any logical,optical, physical or electrical connection, link or the like by whichelectrical or magnetic signals produced or supplied by one systemelement are imparted to another coupled or connected element. Unlessdescribed otherwise, coupled or connected elements or devices are notnecessarily directly connected to one another and may be separated byintermediate components, elements or communication media that maymodify, manipulate or carry the electrical signals. The term “on” meansdirectly supported by an element or indirectly supported by the elementthrough another element integrated into or supported by the element.

The orientations of the eyewear device, associated components and anycomplete devices incorporating a depth-capturing camera such as shown inany of the drawings, are given by way of example only, for illustrationand discussion purposes. In operation for camera misalignmentcompensation, the eyewear device may be oriented in any other directionsuitable to the application of the eyewear device, for example up, down,sideways, or any other orientation. Also, to the extent used herein, anydirectional term, such as front, rear, inwards, outwards, towards, left,right, lateral, longitudinal, up, down, upper, lower, top, bottom, side,horizontal, vertical, and diagonal are used by way of example only, andare not limiting as to direction or orientation of any depth-capturingcamera or component of the depth-capturing camera constructed asotherwise described herein.

Additional objects, advantages and novel features of the examples willbe set forth in part in the following description, and in part willbecome apparent to those skilled in the art upon examination of thefollowing and the accompanying drawings or may be learned by productionor operation of the examples. The objects and advantages of the presentsubject matter may be realized and attained by means of themethodologies, instrumentalities and combinations particularly pointedout in the appended claims.

Reference now is made in detail to the examples illustrated in theaccompanying drawings and discussed below.

As shown in FIGS. 1A and 1B, the eyewear device 100 includes a rightvisible light camera 114B. The eyewear device 100 can include multiplevisible light cameras 114A and 114B that form a passive type ofdepth-capturing camera, such as stereo camera, of which the rightvisible light camera 114B is located on a right electronic housing 110B.As shown in FIGS. 1C and 1D, the eyewear device 100 also includes a leftvisible light camera 114A.

Left and right visible light cameras 114A and 114B are sensitive to thevisible light range wavelength. Each of the visible light cameras 114Aand 114B have a different frontward facing field of view which areoverlapping to allow three-dimensional depth images to be generated, forexample, right visible light camera 114B has the depicted right field ofview 111B (see FIGS. 8A and 8B). Generally, a “field of view” is thepart of the scene that is visible through the camera at a position andorientation in space. Objects or object features outside the field ofview 111A and 111B when the image is captured by the visible lightcamera are not recorded in a raw image (e.g., photograph or picture).The field of view describes an angle range or extent which the imagesensor of the visible light camera 114A and 114B picks upelectromagnetic radiation of a given scene in a captured image of thegiven scene. Field of view can be expressed as the angular size of theview cone, i.e., an angle of view. The angle of view can be measuredhorizontally, vertically, or diagonally.

In an example, visible light cameras 114A and 114B have a field of viewwith an angle of view between 15° to 30°, for example 24°, and have aresolution of 480×480 pixels or greater. The “angle of coverage”describes the angle range that a lens of visible light cameras 114A and114B or infrared camera 220 (see FIG. 2A) can effectively image.Typically, the image circle produced by a camera lens is large enough tocover the film or sensor completely, possibly including some vignetting(i.e., a reduction of an image's brightness or saturation at theperiphery compared to the image center). If the angle of coverage of thecamera lens does not fill the sensor, the image circle will be visible,typically with strong vignetting toward the edge, and the effectiveangle of view will be limited to the angle of coverage.

Examples of such visible lights camera 114A and 114B include ahigh-resolution complementary metal-oxide-semiconductor (CMOS) imagesensor and a video graphic array (VGA) camera, such as 640 p (e.g.,640×480 pixels for a total of 0.3 megapixels), 720 p, or 1080 p. As usedherein, the term “overlapping” when referring to field of view means thematrix of pixels in the generated raw image(s) or infrared image of ascene overlap by 30% or more. As used herein, the term “substantiallyoverlapping” when referring to field of view means the matrix of pixelsin the generated raw image(s) or infrared image of a scene overlap by50% or more. Suitable visible light cameras 114 include complementarymetal-oxide-semiconductor (CMOS) sensor cameras with rolling shutterreadout. In one example, the cameras 114 include a V-blank periodsetting for use in minimizing the time difference, T, between featurepoints obtained by two separate cameras. In another example, the cameras114 include an exposure delay setting that is counted in sensor lines,such as cameras available from Sony Corporation of Minato, Japan, topostpose readout of one of the cameras in order to expose feature pointsfalling on different lines at substantially the same time. Othersuitable cameras will be understood by one of skill in the art from thedescription herein.

Image sensor data from the visible light cameras 114A and 114B arecaptured along with geolocation data, digitized by an image processor,and stored in a memory. The captured left and right raw images capturedby respective visible light cameras 114A and 114B are in thetwo-dimensional space domain and comprise a matrix of pixels on atwo-dimensional coordinate system that includes an X axis for horizontalposition and a Y axis for vertical position. Each pixel includes a colorattribute (e.g., a red pixel light value, a green pixel light value,and/or a blue pixel light value); and a position attribute (e.g., an Xlocation coordinate and a Y location coordinate).

To provide stereoscopic vision, visible light cameras 114A and 114B maybe coupled to an image processor (element 912 of FIG. 9) for digitalprocessing along with a timestamp in which the image of the scene iscaptured. Image processor 912 includes circuitry to receive signals fromthe visible light cameras 114A and 114B and process those signals fromthe visible light camera 114 into a format suitable for storage in thememory. The timestamp can be added by the image processor or otherprocessor, which controls operation of the visible light cameras 114Aand 114B. Visible light cameras 114A and 114B allow the depth-capturingcamera to simulate human binocular vision. The depth-capturing cameraprovides the ability to reproduce three-dimensional images based on twocaptured images from the visible light cameras 114A and 114B having thesame timestamp. Such three-dimensional images allow for an immersivelife-like experience, e.g., for virtual reality or video gaming.Three-dimensional depth videos may be produced by stitching together asequence of three-dimensional depth images with associated timecoordinates for a presentation time in a depth video.

For stereoscopic vision, a pair of raw red, green, and blue (RGB) imagesare captured of a scene at a moment in time—one image for each of theleft and right visible light cameras 114A and 114B. When the pair ofcaptured raw images from the frontward facing left and right field ofviews 111A and 111B of the left and right visible light cameras 114A and114B are processed (e.g., by the image processor), depth images aregenerated, and the generated depth images can be perceived by a user onthe optical assembly 180A and 180B or other image display(s) (e.g., of amobile device). The generated depth images are in the three-dimensionalspace domain and can comprise a matrix of vertices on athree-dimensional location coordinate system that includes an X axis forhorizontal position (e.g., length), a Y axis for vertical position(e.g., height), and a Z axis for a depth position (e.g., distance).

A depth video further associates each of a sequence of generated depthimages with a time coordinate on a time (T) axis for a presentation timein a depth video (e.g., each depth image includes spatial components aswell as a temporal component). The depth video can further include oneor more input parameter components (e.g., an audio component such as anaudio track or stream, a biometric comp such as a heartrate graph,etc.), which may be captured by an input device such as a microphone ora heartrate monitor. Each vertex includes a color attribute (e.g., a redpixel light value, a green pixel light value, and/or a blue pixel lightvalue); a position attribute (e.g., an X location coordinate, a Ylocation coordinate, and a Z location coordinate); a texture attribute,and/or a reflectance attribute. The texture attribute quantifies theperceived texture of the depth image, such as the spatial arrangement ofcolor or intensities in a region of vertices of the depth image.

Generally, perception of depth arises from the disparity of a given 3Dpoint in the left and right raw images captured by visible light cameras114A and 114B. Disparity is the difference in image location of the same3D point when projected under perspective of the visible light cameras114A and 114B (d=x_(left)x_(right)). For visible light cameras 114A and114B with parallel optical axes, focal length f, baseline b, andcorresponding image points (x_(left), y_(left)) and (x_(right),y_(right)), the location of a 3D point (Z axis location coordinate) canbe derived utilizing triangulation which determines depth fromdisparity. Typically, depth of the 3D point is inversely proportional todisparity. A variety of other techniques can also be used for thegeneration of three-dimensional depth images.

In an example, a camera misalignment compensation system includes theeyewear device 100. The eyewear device 100 includes a frame 105 and aleft temple 110A extending from a left lateral side 170A of the frame105 and a right temple 110B extending from a right lateral side 170B ofthe frame 105. Eyewear device 100 further includes a depth-capturingcamera. The depth-capturing camera includes: (i) at least two visiblelight cameras with overlapping fields of view; or (ii) a least onevisible light camera 114A and 114B and a depth sensor (element 213 ofFIG. 2A). In one example, the depth-capturing camera includes a leftvisible light camera 114A with a left field of view 111A connected tothe frame 105 or the left temple 110A to capture a left image of thescene. Eyewear device 100 further includes a right visible light camera114B connected to the frame 105 or the right temple 110B with a rightfield of view 111B to capture (e.g., simultaneously with the leftvisible light camera 114A) a right image of the scene which partiallyoverlaps the left image.

The camera misalignment compensation system further includes a computingdevice, such as a host computer (e.g., mobile device 990 of FIGS. 9 and10) coupled to eyewear device 100 over a network. The cameramisalignment compensation system further includes an image display(optical assembly 180A and 180B of eyewear device; image display 1080 ofmobile device 990 of FIG. 10) for presenting (e.g., displaying) a videoincluding images. The camera misalignment compensation system furtherincludes an image display driver (element 942 of eyewear device 100 ofFIG. 9; element 1090 of mobile device 990 of FIG. 10) coupled to theimage display (optical assembly 180A and 180B of eyewear device; imagedisplay 1080 of mobile device 990 of FIG. 10) to control the imagedisplay to present the initial video.

In some examples, user input is received to indicate that the userdesires to capture an image. For example, the camera misalignmentcompensation system further includes a user input device to receive auser input. Examples of user input devices include a touch sensor(element 991 of FIG. 9 for the eyewear device 100), a touch screendisplay (element 1091 of FIG. 10 for the mobile device 1090), and acomputer mouse for a personal computer or a laptop computer. The cameramisalignment compensation system further includes a processor (element932 of eyewear device 100 of FIG. 9; element 1030 of mobile device 990of FIG. 10) coupled to the eyewear device 100 and the depth-capturingcamera. The camera misalignment compensation system further includes amemory (element 934 of eyewear device 100 of FIG. 9; elements 1040A-B ofmobile device 990 of FIG. 10) accessible to the processor, andprogramming in the memory (element 945 of eyewear device 100 of FIG. 9;element 945 of mobile device 990 of FIG. 10), for example in the eyeweardevice 100 itself, mobile device (element 990 of FIG. 9), or anotherpart of the camera misalignment compensation system (e.g., server system998 of FIG. 9).

Execution of the camera misalignment programming (element 945 of FIG. 9)by the processor (element 932 of FIG. 9) configures the eyewear device100 to compensate for camera misalignment when processing raw images858A-B after rectification. Each of the initial depth images isassociated with a time coordinate on a time (T) axis for a presentationtime, for example, based on initial images 957A-B in the initial video.The initial depth image is formed of a matrix of vertices. Each vertexrepresents a pixel in a three-dimensional scene. Each vertex has aposition attribute. The position attribute of each vertex is based on athree-dimensional location coordinate system and includes an X locationcoordinate on an X axis for horizontal position, a Y location coordinateon a Y axis for vertical position, and a Z location coordinate on a Zaxis for a depth position.

Execution of the camera misalignment compensation programming (element945 of FIG. 10) by the processor (element 945 of FIG. 10) configures themobile device (element 990 of FIG. 10) of the camera misalignmentcompensation system to perform the following functions. Mobile device(element 990 of FIG. 10) identifies a pitch angle offset between theleft and right visible light camera 114 (or between a visible lightcamera and an infrared depth camera). Mobile device (element 990 of FIG.10) then determines misalignment of the first and second cameras fromthe identified pitch angle offset. Next, mobile device (element 990 ofFIG. 10) produces a stereoscopic image on the display from the first andsecond image streams with the introduced relative compensation delay tocompensate for the pitch angle offset.

FIG. 1B is a top cross-sectional view of a right electronic housing 110Bof the eyewear device 100 of FIG. 1A depicting the right visible lightcamera 114B of the depth-capturing camera, and a circuit board. FIG. 1Cis a left side view of an example hardware configuration of an eyeweardevice 100 of FIG. 1A, which shows a left visible light camera 114A ofthe depth-capturing camera. FIG. 1D is a top cross-sectional view of aleft electronic housing 110A of the eyewear device of FIG. 1C depictingthe left visible light camera 114A of the depth-capturing camera, and acircuit board. Construction and placement of the left visible lightcamera 114A is substantially similar to the right visible light camera114B, except the connections and coupling are on the left lateral side170A. As shown in the example of FIG. 1B, the eyewear device 100includes the right visible light camera 114B and a circuit board, whichmay be a flexible printed circuit board (PCB) 140B. The right hinge 126Bconnects the right electronic housing 110B to a right temple 125B of theeyewear device 100. In some examples, components of the right visiblelight camera 114B, the flexible PCB 140B, or other electrical connectorsor contacts may be located on the right temple 125B or the right hinge126B.

The right electronic housing 110B includes electronic housing body 211and an electronic housing cap, with the electronic housing cap omittedin the cross-section of FIG. 1B. Disposed inside the right electronichousing 110B are various interconnected circuit boards, such as PCBs orflexible PCBs, that include controller circuits for right visible lightcamera 114B, microphone(s), low-power wireless circuitry (e.g., forwireless short-range network communication via Bluetooth™), high-speedwireless circuitry (e.g., for wireless local area network communicationvia Wi-Fi).

The right visible light camera 114B is coupled to or disposed on theflexible PCB 240 and covered by a visible light camera cover lens, whichis aimed through opening(s) formed in the frame 105. For example, theright rim 107B of the frame 105 is connected to the right electronichousing 110B and includes the opening(s) for the visible light cameracover lens. The frame 105 includes a front-facing side configured toface outwards away from the eye of the user. The opening for the visiblelight camera cover lens is formed on and through the front-facing side.In the example, the right visible light camera 114B has an outwardfacing field of view 111B with a line of sight or perspective of theright eye of the user of the eyewear device 100. The visible lightcamera cover lens can also be adhered to an outward facing surface ofthe right electronic housing 110B in which an opening is formed with anoutward facing angle of coverage, but in a different outward direction.The coupling can also be indirect via intervening components.

Left (first) visible light camera 114A is connected to a left imagedisplay of left optical assembly 180A and captures a left eye viewedscene observed by a wearer of the eyewear device 100 in a left rawimage. Right (second) visible light camera 114B is connected to a rightimage display of right optical assembly 180B and captures a right eyeviewed scene observed by the wearer of the eyewear device 100 in a rightraw image. The left raw image and the right raw image partially overlapfor use in presenting a three-dimensional observable space of agenerated depth image.

Flexible PCB 140B is disposed inside the right electronic housing 110Band is coupled to one or more other components housed in the rightelectronic housing 110B. Although shown as being formed on the circuitboards of the right electronic housing 110B, the right visible lightcamera 114B can be formed on the circuit boards of the left electronichousing 110A, the temples 125A and 125B, or frame 105.

FIG. 2A is a side view of another example hardware configuration of aneyewear device 100 utilized in the camera misalignment compensationsystem. As shown, the depth-capturing camera includes a left visiblelight camera 114A and a depth sensor 213 on a frame 105 to generate aninitial depth image of a sequence of initial depth images (e.g., in aninitial video). Instead of utilizing at least two visible light cameras114A and 114B to generate the initial depth image, here a single visiblelight camera 114A and the depth sensor 213 are utilized to generatedepth images. The infrared camera 220 of the depth sensor 213 has anoutward facing field of view that substantially overlaps with the leftvisible light camera 114A for a line of sight of the eye of the user. Asshown, the infrared emitter 215 and the infrared camera 220 areco-located on the upper portion of the left rim 107A with the leftvisible light camera 114A.

In the example of FIG. 2A, the depth sensor 213 of the eyewear device100 includes an infrared emitter 215 and an infrared camera 220 whichcaptures an infrared image. Visible light cameras 114A and 114Btypically include a blue light filter to block infrared light detection,in an example, the infrared camera 220 is a visible light camera, suchas a low resolution video graphic array (VGA) camera (e.g., 640×480pixels for a total of 0.3 megapixels), with the blue filter removed. Theinfrared emitter 215 and the infrared camera 220 are co-located on theframe 105, for example, both are shown as connected to the upper portionof the left rim 107A. As described in further detail below, the frame105 or one or more of the left and right electronic housings 110A and110B include a circuit board that includes the infrared emitter 215 andthe infrared camera 220. The infrared emitter 215 and the infraredcamera 220 can be connected to the circuit board by soldering, forexample.

Other arrangements of the infrared emitter 215 and infrared camera 220can be implemented, including arrangements in which the infrared emitter215 and infrared camera 220 are both on the right rim 107A, or indifferent locations on the frame 105, for example, the infrared emitter215 is on the left rim 107B and the infrared camera 220 is on the rightrim 107B. However, the at least one visible light camera 114A and thedepth sensor 213 typically have substantially overlapping fields of viewto generate three-dimensional depth images. In another example, theinfrared emitter 215 is on the frame 105 and the infrared camera 220 ison one of the electronic housings 110A and 110B, or vice versa. Theinfrared emitter 215 can be connected essentially anywhere on the frame105, left electronic housing 110A, or right electronic housing 110B toemit a pattern of infrared in the light of sight of the eye of the user.Similarly, the infrared camera 220 can be connected essentially anywhereon the frame 105, left electronic housing 110A, or right electronichousing 110B to capture at least one reflection variation in the emittedpattern of infrared light of a three-dimensional scene in the light ofsight of the eye of the user.

The infrared emitter 215 and infrared camera 220 are arranged to faceoutwards to pick up an infrared image of a scene with objects or objectfeatures that the user wearing the eyewear device 100 observes. Forexample, the infrared emitter 215 and infrared camera 220 are positioneddirectly in front of the eye, in the upper part of the frame 105 or inthe electronic housings 110A and 110B at either ends of the frame 105with a forward facing field of view to capture images of the scene whichthe user is gazing at, for measurement of depth of objects and objectfeatures.

In one example, the infrared emitter 215 of the depth sensor 213 emitsinfrared light illumination in the forward-facing field of view of thescene, which can be near-infrared light or other short-wavelength beamof low-energy radiation. Alternatively, or additionally, the depthsensor 213 may include an emitter that emits other wavelengths of lightbesides infrared and the depth sensor 213 further includes a camerasensitive to that wavelength that receives and captures images with thatwavelength. As noted above, the eyewear device 100 is coupled to aprocessor and a memory, for example in the eyewear device 100 itself oranother part of the camera misalignment compensation system. Eyeweardevice 100 or the camera misalignment compensation system cansubsequently process the captured infrared image during generation ofthree-dimensional depth images of the depth videos, such as the initialdepth images from the initial video.

FIGS. 2B and 2C are rear views of example hardware configurations of theeyewear device 100, including two different types of image displays.Eyewear device 100 is in a form configured for wearing by a user, whichare eyeglasses in the example. The eyewear device 100 can take otherforms and may incorporate other types of frameworks, for example, aheadgear, a headset, or a helmet.

In the eyeglasses example, eyewear device 100 includes a frame 105including a left rim 107A connected to a right rim 107B via a bridge 106adapted for a nose of the user. The left and right rims 107A-B includerespective apertures 175A and 175B which hold a respective opticalelement 180A and 180B, such as a lens and a display device. As usedherein, the term lens is meant to cover transparent or translucentpieces of glass or plastic having curved and/or flat surfaces that causelight to converge/diverge or that cause little or no convergence ordivergence.

Although shown as having two optical elements 180A and 180B, the eyeweardevice 100 can include other arrangements, such as a single opticalelement or may not include any optical element 180A and 180B dependingon the application or intended user of the eyewear device 100. Asfurther shown, eyewear device 100 includes a left electronic housing110A (including a left camera 114A) adjacent the left lateral side 170Aof the frame 105 and a right electronic housing 110B (including a rightcamera 114B) adjacent the right lateral side 170B of the frame 105. Theelectronic housings 110A and 110B may be integrated into the frame 105on the respective sides 170A and 170B (as illustrated) or implemented asseparate components attached to the frame 105 on the respective sides170A and 170B. Alternatively, the electronic housings 110A and 110B maybe integrated into temples (not shown) attached to the frame 105.

In one example, the image display of the optical assembly 180A and 180Bincludes an integrated image display. As shown in FIG. 2B, the opticalassembly 180A and 180B includes a suitable display matrix 170 of anysuitable type, such as a liquid crystal display (LCD), an organiclight-emitting diode (OLED) display, or any other such display. Theoptical assembly 180A and 180B also includes an optical layer or layers176, which can include lenses, optical coatings, prisms, mirrors,waveguides, optical strips, and other optical components in anycombination.

The optical layers 176A-N can include a prism having a suitable size andconfiguration and including a first surface for receiving light fromdisplay matrix and a second surface for emitting light to the eye of theuser. The prism of the optical layers 176A-N extends over all or atleast a portion of the respective apertures 175A and 175B formed in theleft and right rims 107A-B to permit the user to see the second surfaceof the prism when the eye of the user is viewing through thecorresponding left and right rims 107A-B. The first surface of the prismof the optical layers 176A-N faces upwardly from the frame 105 and thedisplay matrix overlies the prism so that photons and light emitted bythe display matrix impinge the first surface. The prism is sized andshaped so that the light is refracted within the prism and is directedtowards the eye of the user by the second surface of the prism of theoptical layers 176A-N. In this regard, the second surface of the prismof the optical layers 176A-N can be convex to direct the light towardsthe center of the eye. The prism can optionally be sized and shaped tomagnify the image projected by the display matrix 170, and the lighttravels through the prism so that the image viewed from the secondsurface is larger in one or more dimensions than the image emitted fromthe display matrix 170.

In another example, the image display device of optical assembly 180Aand 180B includes a projection image display as shown in FIG. 2C. Theoptical assembly 180A and 180B includes a laser projector 150, which isa three-color laser projector using a scanning mirror or galvanometer.During operation, an optical source such as a laser projector 150 isdisposed in or on one of the temples 125A and 125B of the eyewear device100. Optical assembly 180A and 180B includes one or more optical strips155A-N spaced apart across the width of the lens of the optical assembly180A and 180B or across a depth of the lens between the front surfaceand the rear surface of the lens.

As the photons projected by the laser projector 150 travel across thelens of the optical assembly 180A and 180B, the photons encounter theoptical strips 155A-N. When a photon encounters an optical strip, thephoton is either redirected towards the user's eye, or it passes to thenext optical strip. A combination of modulation of laser projector 150,and modulation of optical strips, may control specific photons or beamsof light. In an example, a processor controls optical strips 155A-N byinitiating mechanical, acoustic, or electromagnetic signals. Althoughshown as having two optical assemblies 180A and 180B, the eyewear device100 can include other arrangements, such as a single or three opticalassemblies, or the optical assembly 180A and 180B may have a differentarrangement depending on the application or intended user of the eyeweardevice 100.

As further shown in FIGS. 2B and 2C, the electronic housings 110A and110B may be integrated into the frame 105 on the respective lateralsides 170A and 170B (as illustrated) or implemented as separatecomponents attached to the frame 105 on the respective sides 170A and170B. Alternatively, the electronic housings 110A and 110B may beintegrated into temples 125A and 125B attached to the frame 105.

In one example, the image display includes a first (left) image displayand a second (right) image display. Eyewear device 100 includes firstand second apertures 175A and 175B which hold a respective first andsecond optical assembly 180A and 180B. The first optical assembly 180Aincludes the first image display (e.g., a display matrix 170A of FIG.2B; or optical strips 155A-N′ and a projector 150A of FIG. 2C). Thesecond optical assembly 180B includes the second image display e.g., adisplay matrix 170B of FIG. 2B; or optical strips 155A-N″ and aprojector 150B of FIG. 2C).

FIG. 3 shows a rear perspective sectional view of the eyewear device ofFIG. 2A depicting an infrared camera 220, a frame front 330, a frameback 335, and a circuit board. The upper portion of the left rim 107A ofthe frame 105 of the eyewear device 100 includes a frame front 330 and aframe back 335. The frame front 330 includes a front-facing sideconfigured to face outward away from the eye of the user. The frame back335 includes a rear-facing side configured to face inward toward the eyeof the user. An opening for the infrared camera 220 is formed on theframe front 330.

As shown in the encircled cross-section 4-4 of the upper middle portionof the left rim 107A of the frame 105, a circuit board, which is aflexible printed circuit board (PCB) 340, is sandwiched between theframe front 330 and the frame back 335. Also shown in further detail isthe attachment of the left electronic housing 110A to the left temple325A via a left hinge 326A. In some examples, components of the depthsensor 213, including the infrared camera 220, the flexible PCB 340, orother electrical connectors or contacts may be located on the lefttemple 325A or the left hinge 326A.

In an example, the left electronic housing 110A includes an electronichousing body 311, an electronic housing cap 312, an inward facingsurface 391 and an outward facing surface 392 (labeled, but notvisible). Disposed inside the left electronic housing 110A are variousinterconnected circuit boards, such as PCBs or flexible PCBs, whichinclude controller circuits for charging a battery, inwards facing lightemitting diodes (LEDs), and outwards (forward) facing LEDs. Althoughshown as being formed on the circuit boards of the left rim 107A, thedepth sensor 213, including the infrared emitter 215 and the infraredcamera 220, can be formed on the circuit boards of the right rim 107B tocaptured infrared images utilized in the generation of three-dimensionaldepth images or depth videos, for example, in combination with rightvisible light camera 114B.

FIG. 4 is a cross-sectional view through the infrared camera 220 and theframe corresponding to the encircled cross-section 4-4 of the eyeweardevice of FIG. 3. Various layers of the eyewear device 100 are visiblein the cross-section of FIG. 4. As shown, the flexible PCB 340 isdisposed on the frame back 335 and connected to the frame front 330. Theinfrared camera 220 is disposed on the flexible PCB 340 and covered byan infrared camera cover lens 445. For example, the infrared camera 220is reflowed to the back of the flexible PCB 340. Reflowing attaches theinfrared camera 220 to electrical contact pad(s) formed on the back ofthe flexible PCB 340 by subjecting the flexible PCB 340 to controlledheat which melts a solder paste to connect the two components. In oneexample, reflowing is used to surface mount the infrared camera 220 onthe flexible PCB 340 and electrically connect the two components.However, through-holes can be used to connect leads from the infraredcamera 220 to the flexible PCB 340 via interconnects, for example.

The frame front 330 includes an infrared camera opening 450 for theinfrared camera cover lens 445. The infrared camera opening 450 isformed on a front-facing side of the frame front 330 that is configuredto face outwards away from the eye of the user and towards a scene beingobserved by the user. In the example, the flexible PCB 340 can beconnected to the frame back 335 via a flexible PCB adhesive 460. Theinfrared camera cover lens 445 can be connected to the frame front 330via infrared camera cover lens adhesive 455. The connection can beindirect via intervening components.

FIG. 5 shows a rear perspective view of the eyewear device of FIG. 2A.The eyewear device 100 includes an infrared emitter 215, infrared camera220, a frame front 330, a frame back 335, and a circuit board 340. As inFIG. 3, it can be seen in FIG. 5 that the upper portion of the left rimof the frame of the eyewear device 100 includes the frame front 330 andthe frame back 335. An opening for the infrared emitter 215 is formed onthe frame front 330.

As shown in the encircled cross-section 6-6 in the upper middle portionof the left rim of the frame, a circuit board, which is a flexible PCB340, is sandwiched between the frame front 330 and the frame back 335.Also shown in further detail is the attachment of the left electronichousing 110A to the left temple 325A via the left hinge 326A. In someexamples, components of the depth sensor 213, including the infraredemitter 215, the flexible PCB 340, or other electrical connectors orcontacts may be located on the left temple 325A or the left hinge 326A.

FIG. 6 is a cross-sectional view through the infrared emitter 215 andthe frame corresponding to the encircled cross-section 6-6 of theeyewear device of FIG. 5. Multiple layers of the eyewear device 100 areillustrated in the cross-section of FIG. 6, as shown the frame 105includes the frame front 330 and the frame back 335. The flexible PCB340 is disposed on the frame back 335 and connected to the frame front330. The infrared emitter 215 is disposed on the flexible PCB 340 andcovered by an infrared emitter cover lens 645. For example, the infraredemitter 215 is reflowed to the back of the flexible PCB 340. Reflowingattaches the infrared emitter 215 to contact pad(s) formed on the backof the flexible PCB 340 by subjecting the flexible PCB 340 to controlledheat which melts a solder paste to connect the two components. In oneexample, reflowing is used to surface mount the infrared emitter 215 onthe flexible PCB 340 and electrically connect the two components.However, through-holes can be used to connect leads from the infraredemitter 215 to the flexible PCB 340 via interconnects, for example.

The frame front 330 includes an infrared emitter opening 650 for theinfrared emitter cover lens 645. The infrared emitter opening 650 isformed on a front-facing side of the frame front 330 that is configuredto face outwards away from the eye of the user and towards a scene beingobserved by the user. In the example, the flexible PCB 340 can beconnected to the frame back 335 via the flexible PCB adhesive 460. Theinfrared emitter cover lens 645 can be connected to the frame front 330via infrared emitter cover lens adhesive 655. The coupling can also beindirect via intervening components.

FIG. 7 depicts an example of an emitted pattern of infrared light 781emitted by an infrared emitter 215 of the depth sensor 213. As shown,reflection variations of the emitted pattern of infrared light 782 arecaptured by the infrared camera 220 of the depth sensor 213 of theeyewear device 100 as an infrared image. The reflection variations ofthe emitted pattern of infrared light 782 is utilized to measure depthof pixels in a raw image (e.g., left raw image) to generatethree-dimensional depth images, such as the initial depth images of asequence of initial depth images (e.g., in an initial video).

Depth sensor 213 in the example includes the infrared emitter 215 toproject a pattern of infrared light and the infrared camera 220 tocapture infrared images of distortions of the projected infrared lightby objects or object features in a space, shown as scene 715 beingobserved by the wearer of the eyewear device 100. The infrared emitter215, for example, may blast infrared light 781 which falls on objects orobject features within the scene 715 like a sea of dots. In someexamples, the infrared light is emitted as a line pattern, a spiral, ora pattern of concentric rings or the like. Infrared light is typicallynot visible to the human eye. The infrared camera 220 is like a standardred, green, and blue (RGB) camera but receives and captures images oflight in the infrared wavelength range. For depth sensing, the infraredcamera 220 is coupled to an image processor (element 912 of FIG. 9) andthe camera misalignment compensation programming (element 945) thatjudge time of flight based on the captured infrared image of theinfrared light. For example, the distorted dot pattern 782 in thecaptured infrared image can then be processed by an image processor todetermine depth from the displacement of dots. Typically, nearby objectsor object features have a pattern with dots spread further apart and faraway objects have a denser dot pattern. The foregoing functionality canbe embodied in programming instructions of camera misalignmentcompensation system programming or application (element 945) found inone or more components of the system.

FIG. 8A depicts an example of infrared light captured by the infraredcamera 220 of the depth sensor 213 with a left infrared camera field ofview 812. Infrared camera 220 captures reflection variations in theemitted pattern of infrared light 782 in the three-dimensional scene 715as an infrared image 859. As further shown, visible light is captured bythe left visible light camera 114A with a left visible light camerafield of view 111A as a left raw image 858A. Based on the infrared image859 and left raw image 858A, the three-dimensional initial depth imageof the three-dimensional scene 715 is generated.

FIG. 8B depicts an example of visible light captured by the left visiblelight camera 114A and visible light captured with a right visible lightcamera 114B. Visible light is captured by the left visible light camera114A with a left visible light camera field of view 111A as a left rawimage 858A. Visible light is captured by the right visible light camera114B with a right visible light camera field of view 111B as a right rawimage 858B. Based on the left raw image 858A and the right raw image858B, the three-dimensional initial depth image of the three-dimensionalscene 715 is generated.

FIG. 8C depicts initial images captured using visible light cameras. Aleft visible light camera (e.g., camera 114A) captures a left raw image800 a including an image feature 802 a of a feature within a scene and aright visible light camera (e.g., camera 114B) captures a right rawimage 800 b including an image feature 802 b of the same feature withinthe scene. Misalignment of the cameras (e.g., due to manufacturingtolerances) results in the image feature 802 a being slightly offset inthe Y-direction (i.e., vertical direction) with respect to the imagefeature 802 b.

FIG. 8D depicts a rectified and compensated left image 804 a and arectified and compensated right image 804 b. A transformation function965 rectifies the images and the camera misalignment and compensationsystem described herein compensates for misalignment between therectified left raw image 800 a and the right raw image 800 b to obtainthe rectified and compensated left image 804 a and right image 804 b. Asseen in FIG. 8D, the image feature 802 a and 802 b lie on the sameraster line 806, which facilitates matching image features to determineoffset in the horizontal direction for use in three-dimensionalrendering.

FIG. 8E depicts a graph 808 showing readout times for image rows for asensor/camera having a rolling shutter in accordance with the prior art.As seen in FIG. 8E, in a rolling shutter camera system, image rows areread out at different times (represented by the solid vertical bars inthe graph 808.

FIG. 8F depicts images captured by a stereoscopic camera system in astatic system (e.g., the cameras and the scene being imaged are notmoving in relation to one another) where the cameras of the camerasystem have different pitch angles. As illustrated in FIG. 8F, theorientation of the left camera (e.g., camera 114A) has a pitch offsetwith respect to the orientation of the right camera (e.g., camera 114B).The pitch offset results in the image feature 802 a being above a rasterline 805 and the image feature 802 b being below the raster line. Due tothe rolling shutter illustrated in FIG. 8E, this may result in the imagefeatures being read out of their respective cameras at different timeswith respect to their expected readouts after synchronization.

FIG. 8G depicts images captured by a stereoscopic camera system in adynamic system (e.g., the cameras and/or the scene being imaged aremoving in relation to one another) where the cameras of the camerasystem have different pitch angles (e.g., the same pitch angledifference as seen in FIG. 8F). As illustrated in FIG. 8G, theorientation of the left camera (e.g., camera 114A) has a pitch offsetwith respect to the orientation of the right camera (e.g., camera 114B).The pitch offset and the dynamic movement results in the image feature802 a being even farther below the raster line 806 than in FIG. 8F. Dueto the rolling shutter illustrated in FIG. 8E, this may result in theimage features being read out of their respective cameras at an evengreater amount of times with respect to their expected readouts aftersynchronization. The amount of time may be greater than tolerances builtinto the system, thereby preventing matching of features forthree-dimensional rendering. In an example, a pitch offset of 3.56degrees may result in a range of 40-75 pixels. Examples described hereinadjust the synchronization to account for the pitch offset in order toremove differences in readout times, thus improving the systems abilityto match features in stereoscopic images.

FIG. 9 is a high-level functional block diagram of an example cameramisalignment compensation system 900, which includes a wearable device(e.g., the eyewear device 100), a mobile device 990, and a server system998 connected via various networks. Eyewear device 100 includes an inputparameter processor and a depth-capturing camera, such as at least oneof the visible light cameras 114A and 114B; and the depth sensor 213,shown as infrared emitter 215 and infrared camera 220. Thedepth-capturing camera can alternatively include at least two visiblelight cameras 114A and 114B (one associated with the left lateral side170A and one associated with the right lateral side 170B).Depth-capturing camera generates initial depth images 961A-N of initialvideo 960, which are rendered three-dimensional (3D) models that aretexture mapped images of red, green, and blue (RGB) imaged scenes. Atransformation function 965 within the wearable device rectifies theinitial images, e.g., to facilitate matching of features and to formatthe images for viewing.

Mobile device 990 may be a smartphone, tablet, laptop computer, accesspoint, or any other such device capable of connecting with eyeweardevice 100 using both a low-power wireless connection 925 and ahigh-speed wireless connection 937. Mobile device 990 is connected toserver system 998 and network 995. The network 995 may include anycombination of wired and wireless connections.

Eyewear device 100 further includes two image displays of the opticalassembly 180A and 180B (one associated with the left lateral side 170Aand one associated with the right lateral side 170B). Eyewear device 100also includes image display driver 942, image processor 912, low-powercircuitry 920, and high-speed circuitry 930. Image display of opticalassembly 180A and 180B are for presenting images and videos, which caninclude a sequence of depth images, such as the initial depth images961A-N from the initial video 960. Image display driver 942 is coupledto the image display of optical assembly 180A and 180B to control theimage display of optical assembly 180A and 180B to present the videoincluding images, such as, for example, the initial depth images 961A-Nof initial video 960. Eyewear device 100 further includes a user inputdevice 991 (e.g., touch sensor) to receive input and selections from auser.

The components shown in FIG. 9 for the eyewear device 100 are located onone or more circuit boards, for example a PCB or flexible PCB, in therims or temples. Alternatively, or additionally, the depicted componentscan be in the electronic housings, frames, hinges, or bridge of theeyewear device 100. Left and right visible light cameras 114A and 114Bcan include digital camera elements such as a complementarymetal-oxide-semiconductor (CMOS) image sensor, charge coupled device, alens, or any other respective visible or light capturing elements thatmay be used to capture data, including images of scenes with unknownobjects.

Eyewear device 100 includes a memory 934 which includes input parameterprogramming and camera misalignment compensation programming 945 toperform a subset or all the functions described herein for cameramisalignment compensation. As shown, memory 934 further includes a leftraw image 858A captured by left visible light camera 114A, a right rawimage 858B captured by right visible light camera 114B, and an infraredimage 859 captured by infrared camera 220 of the depth sensor 213.

As shown, eyewear device 100 includes an orientation sensor, whichincludes, for example, an inertial measurement unit (IMU) 972 asdepicted. Generally, an inertial measurement unit 972 is an electronicdevice that measures and reports a body's specific force, angular rate,and sometimes the magnetic field surrounding the body, using acombination of accelerometers and gyroscopes, sometimes alsomagnetometers. In this example, the inertial measurement unit 972determines a head orientation of a wearer of the eyewear device 100which correlates to a camera orientation of the depth-capturing cameraof the eyewear device 100 when the associated depth image is captured.The inertial measurement unit 972 works by detecting linear accelerationusing one or more accelerometers and rotational rate using one or moregyroscopes. Typical configurations of inertial measurement units containone accelerometer, gyro, and magnetometer per axis for each of the threeaxes: horizontal axis for left-right movement (X), vertical axis (Y) fortop-bottom movement, and depth or distance axis for up-down movement(Z). The gyroscope detects the gravity vector. The magnetometer definesthe rotation in the magnetic field (e.g., facing south, north, etc.)like a compass which generates a heading reference. The threeaccelerometers detect acceleration along the horizontal (X), vertical(Y), and depth (Z) axes defined above, which can be defined relative tothe ground, the eyewear device 100, the depth-capturing camera, or theuser wearing the eyewear device 100.

Memory 934 includes head orientation measurements which correspond toprincipal axes measurements on the horizontal axis (X axis), verticalaxis (Y axis), and depth or distance axis (Z axis) as tracked (e.g.,measured) by the inertial measurement unit 972. The head orientationmeasurements are utilized to determine alignment of the depth-capturingcamera, which can be used to identify a floor plane of the initial depthimages 961A-N. In certain applications of IMUs, the principal axes arereferred to as pitch, roll, and yaw axes.

Memory 934 further includes multiple initial depth images 961A-N, whichare generated, via the depth-capturing camera. Memory 934 furtherincludes an initial video 960 which includes a sequence of the initialdepth images 961A-N and associated time coordinates. A flowchartoutlining functions which can be implemented in the camera misalignmentcompensation programming 945 is shown in FIG. 11.

As shown in FIG. 9, high-speed circuitry 930 includes high-speedprocessor 932, memory 934, and high-speed wireless circuitry 936. In theexample, the image display driver 942 is coupled to the high-speedcircuitry 930 and operated by the high-speed processor 932 in order todrive the left and right image displays of the optical assembly 180A and180B. High-speed processor 932 may be any processor capable of managinghigh-speed communications and operation of any general computing systemneeded for eyewear device 100. High-speed processor 932 includesprocessing resources needed for managing high-speed data transfers onhigh-speed wireless connection 937 to a wireless local area network(WLAN) using high-speed wireless circuitry 936. In some examples, thehigh-speed processor 932 executes an operating system such as a LINUXoperating system or other such operating system of the eyewear device100 and the operating system is stored in memory 934 for execution. Inaddition to any other responsibilities, the high-speed processor 932executing a software architecture for the eyewear device 100 managesdata transfers with high-speed wireless circuitry 936. In some examples,high-speed wireless circuitry 936 is configured to implement Instituteof Electrical and Electronic Engineers (IEEE) 802.11 communicationstandards, also referred to herein as Wi-Fi. In other examples, otherhigh-speed communications standards may be implemented by high-speedwireless circuitry 936.

Low-power wireless circuitry 924 and the high-speed wireless circuitry936 of the eyewear device 100 can include short range transceivers(Bluetooth™) and wireless wide, local, or wide area network transceivers(e.g., cellular or Wi-Fi). Mobile device 990, including the transceiverscommunicating via the low-power wireless connection 925 and high-speedwireless connection 937, may be implemented using details of thearchitecture of the eyewear device 100, as can other elements of network995.

Memory 934 includes any storage device capable of storing various dataand applications, including, among other things, camera data generatedby the left and right visible light cameras 114A and 114B, infraredcamera 220, and the image processor 912, as well as images and videosgenerated for display by the image display driver 942 on the imagedisplays of the optical assembly 180A and 180B. While memory 934 isshown as integrated with high-speed circuitry 930, in other examples,memory 934 may be an independent standalone element of the eyeweardevice 100. In some such examples, electrical routing lines may providea connection through a chip that includes the high-speed processor 932from the image processor 912 or low-power processor 922 to the memory934. In other examples, the high-speed processor 932 may manageaddressing of memory 934 such that the low-power processor 922 will bootthe high-speed processor 932 any time that a read or write operationinvolving memory 934 is needed.

As shown in FIG. 9, the processor 932 of the eyewear device 100 can becoupled to the depth-capturing camera (visible light cameras 114A and114B; or visible light camera 114A, infrared emitter 215, and infraredcamera 220), the image display driver 942, the user input device 991,and the memory 934. As shown in FIG. 10, the processor 1030 of themobile device 990 can be coupled to the depth-capturing camera 1070, theimage display driver 1090, the user input device 1091, and the memory1040A. Eyewear device 100 can perform all or a subset of any of thefollowing functions described below as a result of the execution of thecamera misalignment compensation programming 945 in the memory 934 bythe processor 932 of the eyewear device 100. Mobile device 990 canperform all or a subset of any of the following functions describedbelow as a result of the execution of the camera misalignmentcompensation programming 945 in the memory 1040A by the processor 1030of the mobile device 990. Functions can be divided in the cameramisalignment compensation system 900, such that the eyewear device 100generates the initial depth images 961A-N from the initial video 960,but the mobile device 990 performs the remainder of the image processingon the initial depth images 961A-N from the initial video 960 tocompensation for misalignment of the cameras.

In one example of the camera misalignment compensation system 900, theprocessor comprises a first processor 932 and a second processor 1030.The memory comprises a first memory 934 and a second memory 1040A. Theeyewear device 100 includes a first network communication 924 or 936interface for communication over a network 925 or 937 (e.g., a wirelessshort-range network or a wireless local area network), the firstprocessor 932 coupled to the first network communication interface 924or 936, and the first memory 934 accessible to the first processor 932.Eyewear device 100 further includes camera misalignment compensationprogramming 945 in the first memory 934. Execution of the cameramisalignment compensation programming 945 by the first processor 932configures the eyewear device 100 to perform the function to capture,via the depth-capturing camera, images.

The camera misalignment compensation system 900 further comprises a hostcomputer, such as the mobile device 990, coupled to the eyewear device100 over the network 925 or 937. The host computer includes a secondnetwork communication interface 1010 or 1020 for communication over thenetwork 925 or 937, the second processor 1030 coupled to the secondnetwork communication interface 1010 or 1020, and the second memory1040A accessible to the second processor 1030. Host computer furtherincludes camera misalignment compensation programming 945 in the secondmemory 1040A.

Execution of the camera misalignment compensation programming 945 by thesecond processor 1030 configures the host computer to perform thefunctions to receive, via the second network communication interface1010 or 1020, the captured images over the network from the eyeweardevice 100. Execution of the camera misalignment compensationprogramming 945 by the second processor 1030 configures the hostcomputer to compensate for misalignment of the cameras and present, viathe image display 1080, the compensated images.

In one example, the depth-capturing camera of the eyewear device 100includes the at least two visible light cameras comprised of a leftvisible light camera 114A with a left field of view 111A and a rightvisible light camera 114B with a right field of view 111B. The leftfield of view 111A and the right field of view 111B have an overlappingfield of view 813 (see FIG. 8B). The depth-capturing camera 1070 of themobile device 990 can be similarly structured.

Generating, via the depth-capturing camera, the initial video 960including the sequence of initial depth images 961A-N and associatedtime coordinates can include all or a subset of the following functions.First, capturing, via the left visible light camera 114A, a left rawimage 858A that includes a left matrix of pixels. Second, capturing, viathe right visible light camera 114B, a right raw image 858B thatincludes a right matrix of pixels. Third, creating a left rectifiedimage 969A from the left raw image 858A and a right rectified image 969Bfrom the right raw image 858B that align the left and right raw images858A-B and remove distortion from a respective lens (e.g., at the edgesof the lens from vignetting) of each of the left and right visible lightcameras 114A and 114B. Fourth, extracting an image disparity 970 bycorrelating pixels in the left rectified image 969A with the rightrectified image 969B to calculate a disparity for each of the correlatedpixels. Fifth, calculating the Z location coordinate of vertices of theinitial depth image 961A based on at least the extracted image disparity970 for each of the correlated pixels. Sixth, ordering each of thegenerated initial depth images 961A-N in the sequence from the initialvideo 960 based on a timestamp that is captured when the left raw image858A and the right raw image 858B are captured and setting an associatedrespective time coordinate of the respective initial depth image 961A-Nto the timestamp.

In an example, the depth-capturing camera of the eyewear device 100includes the at least one visible light camera 114A and the depth sensor213 (e.g., infrared emitter 215 and infrared camera 220). The at leastone visible light camera 114A and the depth sensor 213 have asubstantially overlapping field of view 812 (see FIG. 8A). The depthsensor 213 includes an infrared emitter 215 and an infrared camera 220.The infrared emitter 215 is connected to the frame 105 or the temple125A and 125B to emit a pattern of infrared light. The infrared camera220 is connected to the frame 105 or the temple 125A and 125B to capturereflection variations in the emitted pattern of infrared light. Thedepth-capturing camera 1070 of the mobile device 990 can be similarlystructured.

Generating, via the depth-capturing camera, the initial depth image 961Acan include all or a subset of the following functions. First,capturing, via the at least one visible light camera 114A, a raw image858A. Second, emitting, via the infrared emitter 215, a pattern ofinfrared light 781 on a plurality of objects or object features locatedin a scene 715 that are reached by the emitted infrared light 781.Third, capturing, via the infrared camera 220, an infrared image 859 ofreflection variations of the emitted pattern of infrared light 782 onthe plurality of objects or object features. Fourth, computing arespective depth from the depth-capturing camera to the plurality ofobjects or object features, based on the infrared image 859 ofreflection variations. Fifth, correlating objects or object features inthe infrared image 859 of reflection variations with the raw image 858A.Sixth, calculating the Z location coordinate of vertices of the initialdepth image 961A based on, at least, the computed respective depth.

In one example, the user input device 991, 1091 includes a touch sensorincluding an input surface and a sensor array that is coupled to theinput surface to receive at least one finger contact inputted from auser. User input device 991, 1091 further includes a sensing circuitintegrated into or connected to the touch sensor and connected to theprocessor 932, 1030. The sensing circuit is configured to measurevoltage to track the at least one finger contact on the input surface.The function of receiving, via the user input device 991, 1091, inputparameter identification from the user includes receiving, on the inputsurface of the touch sensor, the at least one finger contact inputtedfrom the user.

A touch-based user input device 991 can be integrated into the eyeweardevice 100. As noted above, eyewear device 100 includes an electronichousing 110A and 110B integrated into or connected to the frame 105 onthe lateral side 170A and 170B of the eyewear device 100. The frame 105,the temple 125A and 125B, or the electronic housing 110A and 110Bincludes a circuit board that includes the touch sensor. The circuitboard includes a flexible printed circuit board. The touch sensor isdisposed on the flexible printed circuit board. The sensor array is acapacitive array or a resistive array. The capacitive array or theresistive array includes a grid that forms a two-dimensional rectangularcoordinate system to track X and Y axes location coordinates.

Server system 998 may be one or more computing devices as part of aservice or network computing system, for example, that include aprocessor, a memory, and network communication interface to communicateover the network 995 with the mobile device 990 and eyewear device 100.Eyewear device 100 is connected with a host computer. For example, theeyewear device 100 is paired with the mobile device 990 via thehigh-speed wireless connection 937 or connected to the server system 998via the network 995.

Output components of the eyewear device 100 include visual components,such as the left and right image displays of optical assembly 180A and180B as described in FIGS. 2B and 2C (e.g., a display such as a liquidcrystal display (LCD), a plasma display panel (PDP), a light emittingdiode (LED) display, a projector, or a waveguide). Left and right imagedisplays of optical assembly 180A and 180B can present the initial video960 including the sequence of initial depth images 961A-N. The imagedisplays of the optical assembly 180A and 180B are driven by the imagedisplay driver 942. Image display driver 942 is coupled to the imagedisplay to control the image display to present the initial video 960.The output components of the eyewear device 100 further include acousticcomponents (e.g., speakers), haptic components (e.g., a vibratorymotor), other signal generators, and so forth. The input components ofthe eyewear device 100, the mobile device 990, and server system 998,may include alphanumeric input components (e.g., a keyboard, a touchscreen configured to receive alphanumeric input, a photo-opticalkeyboard, or other alphanumeric input components), point-based inputcomponents (e.g., a mouse, a touchpad, a trackball, a joystick, a motionsensor, or other pointing instruments), tactile input components (e.g.,a physical button, a touch screen that provides location and force oftouches or touch gestures, or other tactile input components), audioinput components (e.g., a microphone), biometric components (e.g., aheart rate monitor) and the like.

Eyewear device 100 may optionally include additional peripheral deviceelements. Such peripheral device elements may include biometric sensors,additional sensors, or display elements integrated with eyewear device100. For example, peripheral device elements may include any I/Ocomponents including output components, motion components, positioncomponents, or any other such elements described herein.

For example, the biometric components include components to detectexpressions (e.g., hand expressions, facial expressions, vocalexpressions, body gestures, or eye tracking), measure biosignals (e.g.,blood pressure, heart rate, body temperature, perspiration, or brainwaves), identify a person (e.g., voice identification, retinalidentification, facial identification, fingerprint identification, orelectroencephalogram based identification), and the like. The motioncomponents include acceleration sensor components (e.g., accelerometer),gravitation sensor components, rotation sensor components (e.g.,gyroscope), and so forth. The position components include locationsensor components to generate location coordinates (e.g., a GlobalPositioning System (GPS) receiver component), Wi-Fi or Bluetooth™transceivers to generate positioning system coordinates, altitude sensorcomponents (e.g., altimeters or barometers that detect air pressure fromwhich altitude may be derived), orientation sensor components (e.g.,magnetometers), and the like. Such positioning system coordinates canalso be received over wireless connections 925 and 937 from the mobiledevice 990 via the low-power wireless circuitry 924 or high-speedwireless circuitry 936.

FIG. 10 is a high-level functional block diagram of an example of amobile device 990. Mobile device 990 includes a user input device 1091and an input parameter processor 1092 to receive user selections. Mobiledevice 990 includes a flash memory 1040A which includes cameramisalignment compensation programming 945 to perform all or a subset ofthe functions described herein for camera misalignment compensation. Asshown, memory 1040A further includes a left raw image 858A captured byleft visible light camera 114A, a right raw image 858B captured by rightvisible light camera 114B, and an infrared image 859 captured byinfrared camera 220 of the depth sensor 213. Mobile device 1090 caninclude a depth-capturing camera 1070 that comprises at least twovisible light cameras (first and second visible light cameras withoverlapping fields of view) or at least on visible light camera and adepth sensor with substantially overlapping fields of view like theeyewear device 100. When the mobile device 990 includes components likethe eyewear device 100, such as the depth-capturing camera, the left rawimage 858A, the right raw image 858B, and the infrared image 859 can becaptured via the depth-capturing camera 1070 of the mobile device 990. Atransformation function 965 within the mobile device rectifies theinitial images, e.g., to facilitate matching of features and to formatthe images for viewing.

Memory 1040A further includes multiple initial depth images 961A-N,which are generated, via the depth-capturing camera of the eyeweardevice 100 or via the depth-capturing camera 1070 of the mobile device990 itself. Memory 1040A further includes an initial video 960 whichincludes a sequence of the initial depth images 961A-N and associatedtime coordinates. Flowcharts outlining functions which can beimplemented in the camera misalignment compensation programming 945 areshown in FIGS. 11A-11C.

As shown, the mobile device 990 includes an image display 1080, an imagedisplay driver 1090 to control the image display, and a user inputdevice 1091 like the eyewear device 100. In the example of FIG. 10, theimage display 1080 and user input device 1091 are integrated togetherinto a touch screen display.

Examples of touch screen type mobile devices that may be used include(but are not limited to) a smart phone, a personal digital assistant(PDA), a tablet computer, a laptop computer, or other portable device.However, the structure and operation of the touch screen type devices isprovided by way of example; and the subject technology as describedherein is not intended to be limited thereto. For purposes of thisdiscussion, FIG. 10 therefore provides block diagram illustrations ofthe example mobile device 990 having a touch screen display fordisplaying content and receiving user input as (or as part of) the userinterface.

As shown in FIG. 10, the mobile device 990 includes at least one digitaltransceiver (XCVR) 1010, shown as WWAN XCVRs, for digital wirelesscommunications via a wide area wireless mobile communication network.The mobile device 990 also includes additional digital or analogtransceivers, such as short range XCVRs 1020 for short-range networkcommunication, such as via NFC, VLC, DECT, ZigBee, Bluetooth™, or Wi-Fi.For example, short range XCVRs 1020 may take the form of any availabletwo-way wireless local area network (WLAN) transceiver of a type that iscompatible with one or more standard protocols of communicationimplemented in wireless local area networks, such as one of the Wi-Fistandards under IEEE 802.11 and WiMAX.

To generate location coordinates for positioning of the mobile device990, the mobile device 990 can include a global positioning system (GPS)receiver. Alternatively, or additionally the mobile device 990 canutilize either or both the short range XCVRs 1020 and WWAN XCVRs 1010for generating location coordinates for positioning. For example,cellular network, Wi-Fi, or Bluetooth™ based positioning systems cangenerate very accurate location coordinates, particularly when used incombination. Such location coordinates can be transmitted to the eyeweardevice over one or more network connections via XCVRs 1010, 1020.

The transceivers 1010, 1020 (network communication interface) conform toone or more of the various digital wireless communication standardsutilized by modern mobile networks. Examples of WWAN transceivers 1010include (but are not limited to) transceivers configured to operate inaccordance with Code Division Multiple Access (CDMA) and 3rd GenerationPartnership Project (3GPP) network technologies including, for exampleand without limitation, 3GPP type 2 (or 3GPP2) and LTE, at timesreferred to as “4G.” For example, the transceivers 1010, 1020 providetwo-way wireless communication of information including digitized audiosignals, still image and video signals, web page information for displayas well as web related inputs, and various types of mobile messagecommunications to/from the mobile device 990.

Several of these types of communications through the transceivers 1010,1020 and a network, as discussed previously, relate to protocols andprocedures in support of communications with the eyewear device 100 orthe server system 998, such as transmitting left raw image 858A, rightraw image 858B, infrared image 859, initial video 960, initial depthimages 961A-N, and time coordinates. Such communications, for example,may transport packet data via the short range XCVRs 1020 over thewireless connections 925 and 937 to and from the eyewear device 100 asshown in FIG. 9. Such communications, for example, may also transportdata utilizing IP packet data transport via the WWAN XCVRs 1010 over thenetwork (e.g., Internet) 995 shown in FIG. 9. Both WWAN XCVRs 1010 andshort range XCVRs 1020 connect through radio frequency (RF)send-and-receive amplifiers (not shown) to an associated antenna (notshown).

The mobile device 990 further includes a microprocessor, shown as CPU1030, sometimes referred to herein as the host controller. A processoris a circuit having elements structured and arranged to perform one ormore processing functions, typically various data processing functions.Although discrete logic components could be used, the examples utilizecomponents forming a programmable CPU. A microprocessor for exampleincludes one or more integrated circuit (IC) chips incorporating theelectronic elements to perform the functions of the CPU. The processor1030, for example, may be based on any known or available microprocessorarchitecture, such as a Reduced Instruction Set Computing (RISC) usingan ARM architecture, as commonly used today in mobile devices and otherportable electronic devices. Other processor circuitry may be used toform the CPU 1030 or processor hardware in smartphone, laptop computer,and tablet.

The microprocessor 1030 serves as a programmable host controller for themobile device 990 by configuring the mobile device 990 to performvarious operations, for example, in accordance with instructions orprogramming executable by processor 1030. For example, such operationsmay include various general operations of the mobile device, as well asoperations related to the camera misalignment compensation programming945 and communications with the eyewear device 100 and server system998. Although a processor may be configured by use of hardwired logic,typical processors in mobile devices are general processing circuitsconfigured by execution of programming.

The mobile device 990 includes a memory or storage device system, forstoring data and programming. In the example, the memory system mayinclude a flash memory 1040A and a random access memory (RAM) 1040B. TheRAM 1040B serves as short term storage for instructions and data beinghandled by the processor 1030, e.g., as a working data processingmemory. The flash memory 1040A typically provides longer term storage.

Hence, in the example of mobile device 990, the flash memory 1040A isused to store programming or instructions for execution by the processor1030. Depending on the type of device, the mobile device 990 stores andruns a mobile operating system through which specific applications,including camera misalignment compensation programming 945, areexecuted. Applications, such as the camera misalignment compensationprogramming 945, may be a native application, a hybrid application, or aweb application (e.g., a dynamic web page executed by a web browser)that runs on mobile device 990. Examples of mobile operating systemsinclude Google Android, Apple iOS (I-Phone or iPad devices), WindowsMobile, Amazon Fire OS, RIM BlackBerry operating system, or the like.

It will be understood that the mobile device 990 is just one type ofhost computer in the camera misalignment compensation system 900 andthat other arrangements may be utilized. For example, a server system998, such as that shown in FIG. 9, may compensated for misalignment inthe depicted images after generation of the initial images 961A-N.

FIGS. 11A, 11B, and 11C are flowcharts 1100, 1120, and 1130 illustratingthe operation of the eyewear device 100 and/or other components of thecamera misalignment compensation system (e.g., one or more of theprocessors 912, 932 executing instructions stored in memory 934). Thesteps are described with reference to hardware described herein but arenot to be limited to such implementations. Although shown as occurringserially, the blocks of FIGS. 11A, 11B, and 11C may be reordered orparallelized depending on the implementation. Furthermore, one of skillin the art will understand from the description herein that one or moresteps/blocks may be omitted, and one or more additional/alternativesteps may be incorporated.

At block 1102, identify a pitch angle offset between sensors/cameras ofa stereoscopic camera system. The stereoscopic camera system may includea first camera 114A and a second camera 114B. In one example,identifying the pitch angle offset includes first determining a firstpitch angle of a first camera (block 1122; FIG. 11B). Then, determininga second pitch angle of a second camera (block 1124; FIG. 11B). And,then, determining the pitch angle offset from a difference between thefirst pitch angle and the second pitch angle (block 1126; FIG. 11B). Thepitch angle offset may be stored in memory (e.g., memory 934) andretrieve through a call (e.g., from processor 932) to determine thepitch angle offset.

In another example, identification of pitch angle offset is based onflexure of the frame. One or more flex sensors (e.g., a Wheatstonebridge on a flexible PCB within the frame of the eyewear device 100)determine flexure of the frame. The amount of flexure corresponds to aflexure offset. The flexure offset may be the identified pitch angleoffset for may be used to adjust pitch angle offset determined inanother manner.

At block 1104, determine misalignment of the first and second camerasfrom the identified pitch angle offset. The misalignment may be a numberof lines or pixels between where an image feature (e.g., image feature802 b in FIG. 8F) would be expected to appear in an image and where itappears in the image (e.g., image feature 802 b in FIG. 8G). Themisalignment may be calculated based on a known relationship betweenpitch angle offset and number of pixels. In an example, a pitch angleoffset of 3.56 degrees may correspond to a range of 40-75 pixels.

At block 1106, determine a relative compensation delay responsive to thedetermined misalignment. In one example, determining the relativecompensation delay includes synchronizing readouts of the first andsecond cameras (block 1132; FIG. 11C). Then, determining an offset timecorresponding to the determined misalignment (block 1134; FIG. 11C).And, then, setting the relative compensation delay to the determinedoffset time (block 1136; FIG. 11C). In another example, determining therelative compensation delay includes determining the relativecompensation delay directly from the determined misalignment withoutfirst determining an offset time.

At block 1108, introduce the relative compensation delay. In oneexample, relative compensation delay is introduced afterexposure/capture, e.g., by changing the vertical blanking interval of acamera in order to minimize compensation delay between feature points offirst and second image streams from first and second cameras. In anotherexample, the relative compensation delay is introduced prior toexposure/capture, e.g., by configuring the exposure delay such thatfeature points are exposed at substantially the same time.

At block 1110, produce a stereoscopic image on the display from firstand second image streams with the introduced relative compensation delayto compensate for the pitch angle offset. In one example, imageprocessor 912 adjusts the image streams for presentation on the imagedisplays 180A and 180B by the image display driver 942.

The camera misalignment compensation functionality described herein forthe eyewear device 100, mobile device 990, and server system 998 can beembodied in one or more applications as described previously. Accordingto some examples, “function,” “functions,” “application,”“applications,” “instruction,” “instructions,” or “programming” areprogram(s) that execute functions defined in the programs. Variousprogramming languages can be employed to create one or more of theapplications, structured in a variety of manners, such asobject-oriented programming languages (e.g., Objective-C, Java, or C++)or procedural programming languages (e.g., C or assembly language). In aspecific example, a third party application (e.g., an applicationdeveloped using the ANDROID™ or IOS™ software development kit (SDK) byan entity other than the vendor of the particular platform) may bemobile software running on a mobile operating system such as IOS™,ANDROID™ WINDOWS® Phone, or another mobile operating systems. In thisexample, the third-party application can invoke API calls provided bythe operating system to facilitate functionality described herein.

Hence, a machine-readable medium may take many forms of tangible storagemedium. Non-volatile storage media include, for example, optical ormagnetic disks, such as any of the storage devices in any computer(s) orthe like, such as may be used to implement the client device, mediagateway, transcoder, etc. shown in the drawings. Volatile storage mediainclude dynamic memory, such as main memory of such a computer platform.Tangible transmission media include coaxial cables; copper wire andfiber optics, including the wires that comprise a bus within a computersystem. Carrier-wave transmission media may take the form of electric orelectromagnetic signals, or acoustic or light waves such as thosegenerated during radio frequency (RF) and infrared (IR) datacommunications. Common forms of computer-readable media thereforeinclude for example: a floppy disk, a flexible disk, hard disk, magnetictape, any other magnetic medium, a CD-ROM, DVD or DVD-ROM, any otheroptical medium, punch cards paper tape, any other physical storagemedium with patterns of holes, a RAM, a PROM and EPROM, a FLASH-EPROM,any other memory chip or cartridge, a carrier wave transporting data orinstructions, cables or links transporting such a carrier wave, or anyother medium from which a computer may read programming code and/ordata. Many of these forms of computer readable media may be involved incarrying one or more sequences of one or more instructions to aprocessor for execution.

The scope of protection is limited solely by the claims that now follow.That scope is intended and should be interpreted to be as broad as isconsistent with the ordinary meaning of the language that is used in theclaims when interpreted in light of this specification and theprosecution history that follows and to encompass all structural andfunctional equivalents. Notwithstanding, none of the claims are intendedto embrace subject matter that fails to satisfy the requirement ofSections 101, 102, or 103 of the Patent Act, nor should they beinterpreted in such a way. Any unintended embracement of such subjectmatter is hereby disclaimed.

Except as stated immediately above, nothing that has been stated orillustrated is intended or should be interpreted to cause a dedicationof any component, step, feature, object, benefit, advantage, orequivalent to the public, regardless of whether it is or is not recitedin the claims.

It will be understood that the terms and expressions used herein havethe ordinary meaning as is accorded to such terms and expressions withrespect to their corresponding respective areas of inquiry and studyexcept where specific meanings have otherwise been set forth herein.Relational terms such as first and second and the like may be usedsolely to distinguish one entity or action from another withoutnecessarily requiring or implying any actual such relationship or orderbetween such entities or actions. The terms “comprises,” “comprising,”“includes,” “including,” or any other variation thereof, are intended tocover a non-exclusive inclusion, such that a process, method, article,or apparatus that comprises or includes a list of elements or steps doesnot include only those elements or steps but may include other elementsor steps not expressly listed or inherent to such process, method,article, or apparatus. An element preceded by “a” or “an” does not,without further constraints, preclude the existence of additionalidentical elements in the process, method, article, or apparatus thatcomprises the element.

Unless otherwise stated, any and all measurements, values, ratings,positions, magnitudes, sizes, and other specifications that are setforth in this specification, including in the claims that follow, areapproximate, not exact. Such amounts are intended to have a reasonablerange that is consistent with the functions to which they relate andwith what is customary in the art to which they pertain. For example,unless expressly stated otherwise, a parameter value or the like mayvary by as much as ±10% from the stated amount.

In addition, in the foregoing Detailed Description, various features aregrouped together in various examples for the purpose of streamlining thedisclosure. This method of disclosure is not to be interpreted asreflecting an intention that the claimed examples require more featuresthan are expressly recited in each claim. Rather, as the followingclaims reflect, the subject matter to be protected lies in less than allfeatures of any single disclosed example. Thus, the following claims arehereby incorporated into the Detailed Description, with each claimstanding on its own as a separately claimed subject matter.

While the foregoing has described what are considered to be the bestmode and other examples, it is understood that various modifications maybe made therein and that the subject matter disclosed herein may beimplemented in various forms and examples, and that they may be appliedin numerous applications, only some of which have been described herein.It is intended by the following claims to claim any and allmodifications and variations that fall within the true scope of thepresent concepts.

What is claimed is:
 1. A camera compensation system comprising: aneyewear device including: a frame; and a stereoscopic camera including afirst camera and a second camera supported by the frame, the firstcamera producing a first image stream and the second camera producing asecond image stream, and the first and second cameras having anoverlapping field of view and a pitch angle offset, whereby featurepoints obtained by the first and second cameras in the first and secondimage streams have a time difference or an exposure delay, the exposuredelay counted in sensor lines whereby the feature points fall ondifferent sensor lines at the same time; an image display for presentinga stereoscopic image produced from the first and second image streams;an image display driver coupled to the image display to control theimage display to present the stereoscopic image responsive to the pitchangle offset; a memory; a processor coupled to the stereoscopic camera,the image display driver, and the memory; and programming in the memory,wherein execution of the programming by the processor configures thecamera compensation system to perform functions, including functions to:identify the pitch angle offset; determine misalignment of the first andsecond cameras from the identified pitch angle offset; determine arelative compensation delay responsive to the determined misalignment;introduce the relative compensation delay to at least one of the firstand second image streams by adjusting the time difference or theexposure delay of the at least one of the first and second cameras priorto capturing the first and second images; and produce a stereoscopicimage on the display from the first and second image streams with theintroduced relative compensation delay to compensate for the pitch angleoffset.
 2. The system of claim 1, wherein execution of the programmingby the processor determines the relative compensation delay byperforming functions to: synchronize readouts of the first and secondcameras; determine an offset time corresponding to the determinedmisalignment; and adjust the relative compensation delay by thedetermined offset time.
 3. The system of claim 1, wherein execution ofthe programming by the processor identifies the pitch angle offset byperforming functions to: determine a first pitch angle of the firstcamera; determine a second pitch angle of the second camera; anddetermine the pitch angle offset from a difference between the firstpitch angle and the second pitch angle.
 4. The system of claim 1,wherein execution of the programming by the processor identifies thepitch angle offset by performing functions to: determine flexure of theframe; and determine the pitch angle offset from the flexure of theframe.
 5. The system of claim 1, wherein the pitch angle offset isstored in the memory and wherein execution of the programming by theprocessor identifies the pitch angle offset by performing functions to:retrieve the pitch angle offset from the memory; and determine the pitchangle offset from the retrieved pitch angle offset.
 6. The system ofclaim 1, wherein execution of the programming by the processordetermines the misalignment of the first and second cameras byperforming functions to: determine a number of offset sensor linesbetween a first plurality of sensor lines and a second plurality ofsensor lines corresponding to the pitch angle offset.
 7. The system ofclaim 6, wherein execution of the programming by the processordetermines the relative compensation delay by performing functions to:determine an offset time corresponding to the number of offset lines;and adjust the relative compensation delay by the determined offsettime.
 8. The system of claim 7, wherein execution of the programming bythe processor determines the relative compensation delay by furtherperforming functions to: synchronize readouts of the first and secondcameras.
 9. The system of claim 1, wherein execution of the programmingby the processor determines the relative compensation delay byperforming functions to: introduce delay after capturing the first andsecond images by changing a vertical blanking interval of at least oneof the first and second cameras in order to minimize compensation delaybetween feature points of the first and second image streams from thefirst and second cameras.
 10. The system of claim 1, wherein executionof the programming by the processor determines the relative compensationdelay by performing functions to: introduce delay prior to capturing thefirst and second images by configuring an exposure delay of at least oneof the first and second cameras such that feature points are exposed atsubstantially the same time.
 11. A camera compensation methodcomprising: identifying a pitch angle offset between a first camera anda second camera of a stereoscopic camera system supported by a frame ofan eyewear device, the first camera producing a first image stream andthe second camera producing a second image stream, and the first andsecond cameras having an overlapping field of view and a pitch angleoffset, whereby feature points obtained by the first and second camerasin the first and second image streams have a time difference or anexposure delay, the exposure delay counted in sensor lines whereby thefeature points fall on different sensor lines at the same time;determining misalignment of the first and second cameras from theidentified pitch angle offset; determining a relative compensation delayresponsive to the determined misalignment; introducing the relativecompensation delay to at least one of the first and second image streamsby adjusting the time difference or the exposure delay of the at leastone of the first and second cameras prior to capturing first and secondimage streams; and producing a stereoscopic image on a display from thefirst and second image streams with the introduced relative compensationdelay to compensate for the pitch angle offset.
 12. The method of claim11, wherein determining the relative compensation delay comprises:determining an offset time corresponding to the determined misalignment;and adjusting the relative compensation delay by the determined offsettime.
 13. The method of claim 12, wherein determining the relativecompensation delay further comprises: synchronizing readouts of thefirst and second cameras.
 14. The method of claim 11, whereindetermining the relative compensation delay comprises: introducing delayafter capturing the first and second images by changing a verticalblanking interval of at least one of the first and second cameras inorder to minimize compensation delay between feature points of the firstand second image streams from the first and second cameras.
 15. Themethod of claim 11, wherein determining the relative compensation delaycomprises: introducing delay prior to capturing the first and secondimages by configuring an exposure delay of at least one of the first andsecond cameras such that feature points are exposed at substantially thesame time.
 16. A non-transitory computer readable medium comprisinginstructions which, when executed by a processor, cause an electronicsystem to: identify a pitch angle offset between a first camera and asecond camera of a stereoscopic camera system supported by a frame of aneyewear device, the first camera producing a first image stream and thesecond camera producing a second image stream, and the first and secondcameras having an overlapping field of view and a pitch angle offset,whereby feature points obtained by the first and second cameras in thefirst and second image streams have a time difference or an exposuredelay, the exposure delay counted in sensor lines whereby the featurepoints fall on different sensor lines at the same time; determinemisalignment of the first and second cameras from the identified pitchangle offset; determine a relative compensation delay responsive to thedetermined misalignment; introduce the relative compensation delay to atleast one of the first and second image streams by adjusting the timedifference or the exposure delay of the at least one of the first andsecond cameras prior to capturing first and second image streams; andproduce a stereoscopic image on a display from the first and secondimage streams with the introduced relative compensation delay tocompensate for the pitch angle offset.
 17. The non-transitory computerreadable medium of claim 16, wherein determining the relativecompensation delay comprises the processor executing instructions to:determine an offset time corresponding to the determined misalignment;and adjust the relative compensation delay by the determined offsettime.
 18. The non-transitory computer readable medium of claim 17,wherein determining the relative compensation delay further comprisesthe processor executing instructions to: synchronize readouts of thefirst and second cameras.
 19. The non-transitory computer readablemedium of claim 16, wherein determining the relative compensation delaycomprises the processor executing instructions to: introduce delay aftercapturing the first and second images by changing a vertical blankinginterval of at least one of the first and second cameras in order tominimize compensation delay between feature points of the first andsecond image streams from the first and second cameras.
 20. Thenon-transitory computer readable medium of claim 16, wherein determiningthe relative compensation delay comprises the processor executinginstructions to: introduce delay prior to capturing the first and secondimages by configuring an exposure delay of at least one of the first andsecond cameras such that feature points are exposed at substantially thesame time.